The invention pertains to semiconductor processing methods and integrated circuitry. The invention has particular application to semiconductor processing methods of depositing aluminum, and to integrated circuitry comprising aluminum.
It is frequently desired to form aluminum within high aspect ratio contact openings during semiconductor fabrication. The contact openings extend through, for example, an insulative material. The aluminum functions as a conductive metal contact within the contact openings. The aluminum also generally extends beyond the contact openings to form wiring interconnect layers which electrically connect the metal contacts within the contact openings to other circuitry. The aluminum extending beyond the contact openings can lie over the insulative material through which the contact openings are formed. Unfortunately, if aluminum is deposited over a material there will frequently be stress-induced voids developed along edges of the deposited aluminum. It would be desirable to develop methods of forming aluminum wherein stress-induced void formation is substantially avoided.
A recently developed method of depositing aluminum is a so-called cold wall chemical vapor deposition (CVD) process, which can use, for example, dimethyl aluminum hydride (DMAH) as an aluminum precursor. The chemical vapor deposited aluminum nucleates better to titanium nitride (TiN) than to many other materials. Accordingly, a TiN layer is frequently provided prior to chemical vapor deposition of aluminum.
In one aspect, the invention encompasses a semiconductor processing method wherein an electrically insulative layer is formed over a substrate. An opening is formed within the electrically insulative layer. The opening has a periphery defined at least in part by a bottom surface and a sidewall surface. A first layer comprising TiN is formed within the opening. The first layer is over the bottom surface and along the sidewall surface. A second layer comprising elemental Ti is formed over the electrically insulative layer. The second layer is substantially not within the opening. The second layer has a thickness of less than 200 Angstroms along the sidewall surface and over the bottom surface. An aluminum-comprising layer is formed within the opening and over the second layer.
In another aspect, the invention encompasses a semiconductor processing method wherein an electrically insulative layer is formed over a substrate. An opening is formed within the electrically insulative layer. The opening has a periphery that is defined at least in part by a bottom surface and a sidewall surface. A first layer comprising TiN is formed within the opening. The first layer formed is over the bottom surface and along the sidewall surface. A second layer comprising elemental Ti is formed over the electrically insulative layer and over the bottom of the opening. The second layer is substantially not along a predominate portion of the sidewall surface. The second layer has a thickness of less than 200 Angstroms along a predominate portion of the sidewall surface and a thickness of at least about 200 Angstroms over the bottom surface. An aluminum-comprising layer is formed within the opening and over the second layer.
In yet another aspect, the invention encompasses a semiconductor processing method wherein an electrically insulative layer is formed over a silicon-comprising substrate. An opening is formed within the electrically insulative layer. The opening extends to the substrate and has a periphery defined in part by a bottom surface. A titanium-silicide layer is formed at the bottom surface. A first layer comprising TiN is formed within the opening and over the titanium silicide. A second layer comprising elemental Ti is formed over the first layer. A first aluminum-comprising layer is formed within the opening and over the second layer. The aluminum-comprising layer contacts the second layer at the bottom surface. A third layer is formed over the first aluminum-comprising layer. The third layer comprises one of elemental Ti or TiN. A second aluminum-comprising layer is formed over the third layer.
In other aspects, the invention encompasses structures formed by the above-described methods.